kubernetes - 需要将哪个 PDB 分配给系统 Pod 以实现集群自动缩放？

Question

在使用集群自动缩放器时，我注意到由于标准的 k8s pod，缩放不起作用:

Fast evaluation: node aks-nodepool1-37748512-0 cannot be removed: non-daemonset, non-mirrored, non-pdb-assignedkube-system pod present: kube-dns-v20-8748686c5-27psn

什么是 kube-dns 的适当 PodDisruptionBudget，标准系统 POD PDB 是否有最佳实践？为什么默认情况下没有配置它们？

Answer 1

关于 Kubernetes 的内部文档 Disruptions我们可以读到:

An Application Owner can create a PodDisruptionBudget object (PDB) for each application. A PDB limits the number pods of a replicated application that are down simultaneously from voluntary disruptions. For example, a quorum-based application would like to ensure that the number of replicas running is never brought below the number needed for a quorum. A web front end might want to ensure that the number of replicas serving load never falls below a certain percentage of the total.

您可以查看有关如何正确启用、调整和禁用 PodDisruptionBudget 的示例。对于 Kubernetes 文档中的 kube-dns Autoscale the DNS Service in a Cluster .

Marton Sereg 也写了一篇关于 Draining Kubernetes nodes 的好文章，其中他解释了排空的工作原理以及集群内部发生的情况。

至于配置默认值，我可以找到这个讨论 Reasonable defaults with eviction and PodDisruptionBudget #35318 .